The Magic That Binds Us
by Biana Delacroix
Summary: Klaus and Caroline would've been happy to forget trespassing where they never should've been. But when they're targeted by an Unspeakable with a deadly secret, they're faced with a threat that could tear them apart and force them to pay the ultimate price


**Author's Note: This fic is the sequel to "All the Magic We Cannot See", I recommend you read that first to make sense of this one (or just jump in, I won't judge.)**

 **This was written as a gift for Angie (Angelikah/thetourguidebarbie) who is one of the best people I have the pleasure to know and has done more for the Klaroline fandom than I can possibly count.**

 **Hope you all enjoy this one!**

* * *

 _Fancy a lunch date? - K_

Caroline smiled to herself despite the purple paper airplane that had floated to her desk and unceremoniously poked her in the head until she paid attention. Trust Klaus's charm on the thing to be annoyingly persistent, just like him.

She couldn't say she minded though.

The clock on the wall ticked down to her lunch hour with agonizing slowness, and Caroline swore there was a spell on the thing, making every second feel like an hour whenever someone looked at it.

(And it would be her fault for taking an office-warming gift from Kol. Little jerk _would_ hang around the confiscated objects department and nick something just to drive her up the wall.)

The seconds did tick down though, and as soon as noon came she was up and out of her desk, heading towards the elevator before anybody could capture her attention. It was difficult keeping still in the back of the lift while bored wizards waited numbly for their floor, ambling much too slowly for Caroline's liking, until the lift's disembodied voice finally called her stop.

 _Level Nine, Department of Mysteries_

She practically flew out of the doors onto Level Nine, heading down the dark corridor fearlessly, a stark contrast to the first time she'd taken the trip down here. Once through the first door there were twelve in front of her, ever changing, meant to protect the secrets of the ministry's most enigmatic department. Only Unspeakables knew how to find their way through this level.

Well, Unspeakables and the people dating them.

As if by invitation, a door to her far left swung open and Caroline practically skipped through and into the waiting arms of Klaus on the other side.

"Miss me, love?" he asked, after kissing her soundly.

"I'd say yes, but your ego doesn't need it." Caroline pulled away slightly, enough that he could wind his arm around her waist and lead her over to his office.

"You wouldn't be so deprived if you'd simply accepted my offer," Klaus reminded her, leading them inside and making quite sure to lock the door behind him. Not that anybody came down here — the department was still avoided by most in the Ministry, and for good reason. But Caroline would never forgive him if anyone ever caught them in a compromising situation, and Klaus adored her too much to refuse her.

"We've been over this," Caroline said, rolling her eyes. "I _like_ being in the Minister's office."

"The Minister's a puppet and you know it sweetheart, Elijah's pulling all the strings. He'll probably be making a run for it when the time comes."

"And when he does, I'll be the perfect candidate for adviser," Caroline said smugly, and Klaus pouted, unable to refute her logic.

"Relax," she cooed, smiling fondly and wrapping her arms around his neck. "If I ever get bored, I'll be right down here with you."

Klaus hid his smile against the soft skin of her neck, nipping kisses along her pulse point, and smirking at the hitch in her breath. "Consider the benefits," he whispered in her ear, backing her into the large oak desk. "We'd see so much more of each other."

Caroline moaned quietly at the feel of his hands gripping the fabric of her robes, pulling them up so that she could slip out of them easily. She wished she had the luxury he did of staying in Muggle clothes, the benefit of his position keeping him out of sight from the rest of the Ministry as well as his ties to Elijah.

Honestly, she couldn't imagine anyone telling Klaus what to do.

Her thoughts were slammed back to the present as Klaus set his hands on her waist and hoisted her easily so that she was sitting on the edge of his desk. He gave her a dirty smirk, keeping his wide lust-blown gaze on her as he sank to his knees, pushing up her pencil skirt.

"One day, we could try actually eating a meal on our lunch breaks," Caroline said breathlessly as she bunched her skirt around her waist.

Klaus simply raised an eyebrow. "I'm afraid my mouth is about to be otherwise occupied."

Caroline gulped, spreading her legs so that he could curl his long fingers around her calf and trail them upwards, leaving goosebumps in their wake. Once he reached the apex of her thighs, he leant forward, pressing a kiss to her hipbone before letting his teeth scrape against her skin and drag the lace of her thong down her legs until it fell to dangle off one heel.

She kicked the material off, letting out a low moan as Klaus made good on his promise and went to work on her pussy, his tongue working more magic than any spell could manage. Caroline had a white-knuckle grip on the desk edge with one hand, the other went to Klaus's curls, running her fingers through them as he teased her to the edge, lips closing over her clit and causing her to see stars.

By the time she came down from her orgasm, Klaus was on his feet and undoing his jeans, and Caroline had never been happier for his disregard of Ministry dress codes.

"Seriously, lunch," she said teasingly as she reached out for him, tugging him closer by his belt loops and wrapping her hand around his cock. "I could try cooking."

"You're not half as talented behind a stove as you are doing this," Klaus growled, too impatient for her teasing. A flick of his hand and his desk cleared, and he wasted no time pushing Caroline down and burying himself in her, delighting in the keen little cry she gave.

Maybe one day they'd manage to remain decent on a lunch break. But today, he had at least one more round to go.

* * *

Caroline righted her robes, patting her hair down one more time. "You could at least get a mirror in here," she teased, turning to face Klaus.

He was leaning against his desk, shamelessly letting his eyes wander over her, and uncrossed his arms to tug her closer, kissing her fondly. "Not a bad idea sweetheart," he murmured against her lips. "I'll put it on the back of the door and then you could watch whenever I bend you over my desk and take you from behind."

It was all too easy to conjure up that image in her mind's eye and Caroline barely held back a moan as Klaus pressed one last warm kiss against the curve of her neck. If he kept this up then she'd definitely be staying for round three, and she had actual work to get back to.

One last kiss — maybe two — and Caroline managed to pry herself away, shutting the door to Klaus's office behind her with a giddy smile playing on her lips. She stepped through the door to the Department's antechamber when movement caught her eye.

For a second Caroline stilled. The door that should always be locked, the one that led to the Department of Mysteries biggest enigma was now ajar — there was someone coming out.

It made sense really, the department didn't just run on Klaus overseeing the Hall of Prophecies, even _he_ had co-workers (who apparently knew to make themselves scarce around this time most days.) But she'd never come across any of the other Unspeakables from the other sections in the short time she'd been working at the Ministry and making her visits down to Klaus.

She should've known that could never last. A young woman with dark skin and curls gently shut the door behind her, affording Caroline only a glimpse of warm bright light, same as the day she'd accidentally stumbled in there. Her mouth ran dry for a second and she wondered if this witch knew anything about that incident. Making a run for it occurred to her, but the Unspeakable looked up and walked forward, an neutral smile on her face.

"I heard rumors that there was someone sneaking visits down here for the past few weeks but I couldn't guess why."

Caroline laughed nervously, bouncing on the balls of her feet. "Oh — it's nothing really, just…checking in?" It was barely an excuse and the witch clearly didn't buy it for a second, but she just smiled wider.

"It's fine you know. Love is something I'm acquainted with." She nodded her head back towards the closed door behind her and Caroline nodded with a wan smile, her mind running wild with memories with what she knew was behind that door.

If the witch noticed her uneasiness, she didn't mention it. Instead, she offered her hand. "Tessa."

"Caroline." They shook hands, and Caroline was a little more at ease, satisfied that she wasn't going to be accused of breaking fifty Ministry rules. She was never totally sure how allowed it was for other employees to just waltz into Level Nine, no matter how glib Klaus was about it.

"Nice to meet you, Caroline," Tessa said with that same odd smile. The longer they stood there, the more Caroline noticed that it didn't quite reach her eyes. "Shall I walk you out?"

There was nothing the blonde could do but agree and so they made their way down the dark corridor that led to the elevator, standing side by side in a heavy silence as the lift's voice counted up.

When the atrium was called, Tessa finally moved to get out. "It was nice to meet you, Caroline," she said over her shoulder. "It's always a pleasure to meet someone who's found their One."

 _Their One?_ Tessa was gone and more wizards filled the lift before Caroline could call out for her and ask for an explanation. She was left to puzzle out the odd comment all the way back up to Level One, but by the time the Minister's office came she made up her mind that anyone who worked in the Department of Mysteries had to be a little off and a strange comment was probably nothing in the grand scheme of things.

That was it. Tessa was weird, all Unspeakables were.

At least the one she was dating was also hot.

* * *

Saturday dawned cold and grey, not that either Klaus or Caroline minded. Wrapped up in each other and under the heavy duvet, neither were set on doing anything that day that involved moving out of Klaus's bed.

"I'm starting to think that getting my own flat was a waste of money," Caroline thought out loud, squirming slightly as Klaus skimmed his fingers up and down her sides.

"Well love, I did tell you as much."

"Kol made a really good case for being flatmates."

"He also asked me to keep you here as much as possible so that he could have girls over — don't look so shocked sweetheart, you're hardly getting a rough deal here." To emphasize his point, Klaus let his hand travel lower until he reached her core, toying with her clit.

Caroline hummed in contentment, not willing to argue her point. Kol _would_ collude with his brother, and Klaus would be more than willing to help if it meant she spent more nights here than in her new flat. The thought of moving in was tempting, practical even — but this was still technically a new relationship and Caroline was nothing if not traditional.

The thought of their relationship took her back to the room in the Ministry and the woman she'd met the other day. It had slipped her mind until now, but since they were both here and not moving anytime soon, it couldn't hurt to ask…

"Have you ever met Tessa?"

Klaus stilled the motions of his hand at her out-of-the-blue question. "Come again?"

"Tessa? I met her the other day. She was coming out of…out of _that_ room."

Klaus had gone completely still, watching her with something between worry and fear. "Did she say—?"

"No!" Caroline assured him quickly. "But she was weird. Said something about how I'd found my 'One'? Do you know what that means?"

Klaus wrapped his arm back around Caroline's waist, pulling her even closer as if he needed the reassurance she was there. "I don't know much about the other sections of the Department outside of the Hall of Prophecies," he said hesitantly. "The Ministry doesn't encourage Unspeakables talking too much, even to each other."

His tone implied there was something he was leaving out. "What is it?" Caroline asked, brow furrowed.

"Tessa studies Love. That's her department."

"Makes sense," Caroline said slowly, thinking back to last year. The fountain in the room was Amortentia, but I couldn't figure out the strings…"

It was the first time either of them had ever mentioned it, the red string that had tied them together, one out of the the millions that crisscrossed the room's cavernous ceiling. They didn't know how it had fallen, why it had wrapped itself around them and, most importantly, why it had disappeared the second they stepped outside. Caroline swore that every now and then, when it was just her and Klaus, she would see the flash of red in the corner of her eye, but nothing was ever there. Just in her imagination. Still, ignoring potentially powerful magic didn't bode well for anyone.

"It's best not to think about it too much," Klaus said, but he sounded more like he was trying to convince himself over her. "No one suspects a thing, it's not worth the hell that it would bring down, not when you've just started on Level One."

He was completely right, Caroline knew, and it's not like she was bursting to tell anyone herself. Still, something about Tessa nagged at her, an unease that she couldn't shake no matter how warm Klaus's arm felt around her. "So Tessa…what's her deal?"

"There are rumours about her —"

"Sounds promising—"

"—but honestly no one knows much of anything. I don't think you could pry it out of Elijah if you tried, even he doesn't have full access to the Department of Mysteries. Unspeakables are under oath to fulfill their duties to their sections and they say that the curses for breaking those oaths are…severe."

Caroline shuddered, burrowing closer into Klaus. It had become significantly less menacing, the Department of Mysteries, mostly because she associated it with the man next to her, but moments like this she was reminded of why it held such a dark reputation, why people avoided it like the plague. Some things are never meant to be known. Not that it stopped people from trying.

"What are the rumours?" Caroline asked hesitantly.

Klaus was quiet a beat too long, and when he finally answered, it was with careful reserve. "A few years back, before I even started in the Ministry, there was apparently some business between her and one of the other Unspeakables."

"What happened?"

"Well that's just it, love." Klaus gently pulled away so that he could look her properly in the eyes, and Caroline could see he was worried. "No one actually knows what happened to the witch who used to have my job."

Caroline released a breath she didn't realize she was holding. "That was how you ended up on Level Nine?"

"There was a vacancy, Elijah pulled some strings, no one asked any questions. They never do."

Silence descended over them, punctuated only by the steady staccato of rain against the window. Caroline regretted ever bringing up the odd witch, worried now that whatever she might've done in the past could somehow hurt Klaus too. As if he sensed her thoughts, Klaus pulled her close and kissed her soundly, pressing her into the sheets.

"Ignore her if you see her again," he said, nipping kisses down her jaw. "It's nothing to worry about."

Caroline disagreed, but it was hard to put up a fight when he was back to trailing his fingers over her heated skin. One more thing nagged at her though.

"Have you ever heard of wizards finding their 'One'?"

Klaus paused, glanced up. "One what?"

"Just…their 'One'?"

"Sweetheart, I don't know what the bloody hell you mean." His tone was light but impatient — he'd much rather put his mouth to better uses. And so without further ado he pulled at the covers until she was completely exposed to him and he could trail his lips over her abdomen, down towards her aching core and all thoughts of the Department and those who work there flew from her mind because right now, it was the two of them and nothing else mattered at all.

* * *

For all the time that Caroline spent in Klaus's bed, it was nice to have a place of her own. Her's _and_ Kol's technically, but it was still where she had her grandma's quilt on her bed and she and Kol bickered over which Muggle show they were going to watch in the evening.

Kol came from a thoroughly pureblood wizarding family, and regardless of how modern the younger generation of Mikaelsons were, it just couldn't match Caroline's knowledge from spending her entire childhood and summers raised by her Muggle mom back in the States. So enchantments existed next to wifi (even if the connection went haywire on a regular basis), Caroline spent hours trying to explain the concept of reality TV ("No Kol, she can't just confound the judges into giving her a perfect score!") and they both took turns learning how to cook with varying degrees of success. Overall, it was home.

"So how's Level Seven?" Caroline asked one evening over a dinner of slightly undercooked pasta. It had taken a bit of cajoling on everyone's part to get Kol to take an interest in an actual job after graduation, but Esther Mikaelson just could not bear one of her sons tarnishing the family name by not entering the Ministry like his brothers before him. The Mikaelson matriarch been hoping for Magical Law, but settled for Kol in the Department of Magical Games and Sports, even if she did try to get Elijah to 'talk sense' into him at every interval.

"It's alright," Kol replied around a mouth full of pasta. "Boring as fuck, but I've met at least a dozen recruiters, and they all remember how good I was in Hogwarts."

"You want to play professionally?"

"I do miss beating things around," Kol said wistfully, while Caroline just snorted into her plate.

"I remember the time you nearly took Tristan de Martel's head off."

"To be fair, it was a rather large target."

Caroline laughed some more as she and Kol bantered back and forth. It was only when their plates were cleared and the conversation lulled for a second that Caroline remembered what had been on her mind the past few days.

"Kol…how much do you know about the Department of Mysteries?"

Kol cocked an eyebrow at her, leaning back into his chair. "Any reason you're asking me and not Nik?"

"I _did_ , but I want to know more. Have you heard any gossip about the Unspeakables that work there?"

Kol pretended to ponder the question for a second. " _Wellll_ ….there is a rumour that one of blokes in the Hall of Prophecies is shagging this hot blonde on Level One."

Caroline chucked a cushion at his head, not impressed. If Hogwarts was bad for gossip, the Ministry was even worse. Thankfully she and Klaus hadn't gotten any flack for their relationship (which wasn't even technically against any rules), but she was hoping that something else had gotten through the grapevine.

"No you dick, _besides_ Klaus. There's this girl named…Tessa? Anything about her?"

Kol chucked the cushion back. "Sorry Sweets, never heard the name."

Caroline sighed, resigned on never learning more about the other Unspeakables. But just as she got up to take her empty plate to the sink, Kol's voice pulled her back.

"I did hear something about an…Amara? The witch used used to work in the Hall of Prophecies?"

Caroline froze, sinking back slowly into her seat. "The one who used to have Klaus's old job?"

Kol nodded, lost in memory. "I was back for the summer before fifth year, Mother was throwing a snit because she'd finally convinced Klaus to work in the Ministry but he refused Level One. Not that I blame him, working with Elijah would be a nightmare, I don't know how you put up with his constant prattling about—"

"Kol! Focus!"

"Christ, don't get your knickers in a twist. Look, Nik was never going to work with the Minister, but there was a vacancy in the Hall of Prophecies that he wanted. And it was his to take really, Elijah and Finn were talking about some business that had gone down with the witch who worked there, apparently she ended up in St. Mungo's, but no one knew why."

Caroline felt a sharp chill on the back of her neck, like someone had walked right over her grave. "No one knew? Was she hurt?"

Kol looked at her oddly. "Well that's the thing, darling. From what I gathered, there was nothing seriously wrong with her…one day she was fine, the next, completely off her rocker."

A beat passed before Caroline managed to speak again. "But you don't know if Tessa did something to her?"

"Told you, I never heard of a 'Tessa'. Granted, that was about the part in the conversation when Rebekah decided to be a bitch and tell Mother about the Extendable Ears I'd gotten from Weasley's earlier that summer—and she confiscated the lot of them too…"

Kol went on to describe how he got back at Rebekah by charming her makeup to give her scales, but Caroline couldn't focus on a word he said. Instead, her mind raced with more questions than answers, wondering about this girl who ended up in St. Mungo's and what had happened to her, what 'Tessa' could possibly have to do with it, why Klaus hadn't thought to tell her any of this when she asked, and most importantly, why she could shake the feeling of dread that had settled over her the more she thought about this story.

There was one thing that hadn't come up though.

"Hey Kol?" she said suddenly, interrupting his story about burning all of his sister's dress robes. "Have you ever heard of wizards finding their 'One'?"

"One what?" he asked, a perfect replica of his older brother.

Caroline sighed and waved him off. It was a stupid thing said by some weird witch who probably just wanted to use the natural mystery of Level Nine and some suspicious rumours to freak Caroline out, that was all. The Department of Mysteries was dangerous, maybe Amara did something she shouldn't have, maybe she tried to view a prophecy that wasn't hers. But that didn't shake the unease Caroline felt over the whole thing, like there was something sinister right under the surface, if only she took the time to look.

Klaus had said that the consequences for breaking the rules there were severe. But Klaus had also clearly lied to her about how much he knew.

One way or another, Caroline was getting her answers.

* * *

Caroline's hands gripped the small flowerpot she was holding on to, muttering a little pep talk to herself under her breath. She didn't know what she was walking into, for the first time in her life she barely had half a plan — _very_ un-Caroline. But these were desperate times, and they called for desperate measures.

If this didn't work, she didn't know what would.

The reception area of St. Mungo's was busy that day, various maladies distracting her as she waited in what felt like an interminably long queue. The welcome-witch at the desk waved each person off to the appropriate ward, clearly bored of her job. Finally, the wizard in front of Caroline with a bad case of uncontrollable giggling was sent to the Third Floor and Caroline stepped up, trying not to squirm under the stare of Dily Derwent's painting above the desk.

"Hi!" Caroline chirped, slightly too-cheerful. "I'm looking for a patient, her name's Amara."

The witch looked up, part bored, part irritated. "Amara who?"

Caroline faltered, trying to keep the smile on her face. "Um, the thing is, I don't actually know her last name. She's…the friend of a friend from the States, and my friend asked me to check up on her since I'm here and they didn't give me a lot of information but I thought I'd come down anyway—"

How much longer Caroline would've gone on for was debatable, but the welcome-witch clearly wasn't buying it and she was spared from further humiliation by a voice from behind her.

"It's Petrova. We're here to see Amara Petrova."

Caroline's breath faltered and she turned slowly to see who had spoken. The man in front of her was tall, with a sharp jawline and deep set eyes that watched her carefully.

"Level Four. Janus Thickey ward," the welcome-witch said from behind her and the stranger smiled over Caroline's shoulder, then nodded his head towards the double doors that led to the staircase. Caroline hesitated for a moment, wondering just what she was getting into, but the burning need for answers drove her to follow the wizard and hope for the best.

"Thanks for that," Caroline said as the double doors closed behind them and they started up the curving staircase, portraits of healers given them unwanted advice as they climbed. "Amara's an — old friend—I just forgot—"

The wizard paused, looking down at her, his lips curving into what would've been a kind smile, except for some reason, Caroline didn't really believe it.

"It's fine, I suppose you knew Amara from when she used to visit her cousins in the States?"

"Yes!" Caroline seized on the opportunity, the lie coming together in her head. "She used to visit in the summers, her cousins are friends of mine — I'm actually visiting for them while I'm here."

The wizard apparently bought it, nodding sagely. "I'm Silas."

Caroline shook the hand he extended. "Caroline Forbes."

They continued up the stairs, studiously ignoring the painting frantically trying to warn Caroline about her impending death from dragon pox before they came to the Fourth Floor. Silas held the door open as they stepped through, then headed towards the Janus Thickey Ward.

"We're here to see Amara Petrova," Silas informed the Healer on duty, and the witch dutifully let them inside. Beds lined the walls and Silas led Caroline to the one at the very end of the row where a young woman sat up, hands folded neatly on her lap. She was pretty, heavy dark curls framing wide doe eyes and a kind smile as she looked over at the rest of the ward with detached interest.

"Hi Amara," Caroline said, placing the small flowerpot on the bedside table. "I'm here because of your…cousins. They send their love."

By some miracle of magic, Amara smiled up at Caroline serenely and didn't question a word she said. Instead, her attention shifted almost immediately to Silas and by the way the man looked down at her, Caroline needed no explanation for why he was here.

"Hello my love," he whispered quietly as he sat down next to her. Caroline felt suddenly that she was intruding on something intensely private and she wanted desperately to flee, only the need for some answers still nagged at her.

"Silas, Amara's cousins didn't say—they just said she was in St. Mungo's, but they didn't tell me that she was in the long term ward. What—what happened to her?"

Caroline prayed she hadn't stuck her foot in her mouth like she usually tended to, but Silas was too enamored with Amara to really pay attention. "There was an accident where she worked," he replied vaguely. "No one really knows what happened."

Amara picked that moment to look up at Caroline, eyes wide but vacant. "Follow the strings," she muttered quietly. "So many strings…"

The blood in Caroline's veins turned to ice as she flashed back to the room in the Department where thousands of red strings criss-crossed a cavernous ceiling. "I don't…I don't know what she means…" Caroline stammered out.

Silas wasn't fazed, just smiled at Amara indulgently. "She doesn't make a lot of sense anymore," he explained. "She just says things. You can ignore it."

"When will they come down?" Amara asked Silas, that wide-dazed look never leaving her eyes. "All the strings, when will they come down?"

Silas didn't answer her, just squeezed her hands on top of the blanket. Caroline fidgeted where she stood, not sure how this was helping. She couldn't interrogate the poor girl, not in the state she was in and definitely not with Silas there. Whatever had happened to her was apparently severe enough to warrant a permanent residence in St. Mungo's and she didn't look like she could string a coherent sentence together, let alone tell Caroline what had happened to her.

"So I'm just going to go," Caroline said finally, ready to put this waste of a visit behind her. "It was nice seeing you Amara. I'll tell your — _cousins_ — that you're okay."

Amara was clearly far from okay but that didn't matter anymore, Caroline had turned on her heel and was ready to get the hell out.

"Follow your string."

Caroline froze, then turned slowly, watching Amara carefully. "Wh-what did you say?"

"Follow your string. It's so pretty," Amara said, serene smile still on her face. "Find your One."

"What does that mean?" Caroline asked her intently, probably a little harsher than she had to. Amara's eyes widened and she cocked her head to the side, gaze sliding to the space on the ground just beside Caroline, but when Caroline turned to see what she was staring at, she saw nothing but the gleaming tile floor.

"I told you. She just says things. They don't mean anything." Silas looked up at Caroline with that same smile that didn't quite reach his eyes and that was enough to get the blonde to nod quickly and turn on her heel, striding out of the ward without a single backwards glance.

The double doors to the staircase were in view and Caroline was just about to wrench them open when the job was done for her. And she did _not_ expect the person on other side.

" _Klaus?!"_

They stared each other down in shock before Klaus finally snapped out of it and looked behind her, towards the closed ward, and then back to Caroline putting two and two together. Caroline saw followed his movements and braced herself for the way his lips pressed together and his brow furrowed, a clear tell of his irritation. Without any preamble he wrapped his fingers around her wrist and tugged her into a nearby broom closet, watching the hallway for healers who were preoccupied with another batch of visitor.s

The door was barely shut behind them when Klaus pulled out his wand, a whispered _"Lumos"_ giving them light. It allowed Caroline to see just how angry he really was.

"Caroline, what the bloody hell are you doing here?!" he hissed.

For a moment, she considered making something up, but he definitely wouldn't believe it and Caroline was getting pretty pissed herself. "You tell me!" she whispered harshly. "But apparently you're lying to me now!"

Klaus jaw ticked as he stared down at her for a long, torturous moment, before finally speaking. "I didn't lie to you," he ground out.

He was met with a scoff. "You didn't tell me everything you knew," Caroline pointed out. "As far as I'm concerned, that's lying."

Klaus turned away from her, scrubbing a hand over his face and when Caroline got a good look at him again, she was slightly taken aback by how tired he looked. As pissed as she was, some of her irritation was quickly being replaced with worry.

"Look, just tell me what the hell is going on," she pleaded, trying to keep her voice even. "I don't know what happened to Amara, but…she had your job, right? Is something wrong? Are you in danger?!"

Her worst fears flew through her mind, of something happening to Klaus in the Department of Mysteries, doomed to become another whispered rumour that she would never learn the truth about. Klaus easily saw the worry on her face, softening and reaching out to pull her closer. The wand he held cast ominous shadows across the small space and Caroline buried her face in Klaus's chest, as if she could hide herself away from them.

"Kol told me you'd asked him about Amara," Klaus whispered against her hair. "I figured you wouldn't stop until you had answers, but I thought if I could figure it out first, then I could at least be the one to explain it to you."

Caroline pulled back to look him in the eye. "Wait…you don't know what happened to her?"

Klaus shook his head grimly. "No one does — and that's the truth, love. Four years ago, Amara was admitted to St. Mungo's after an incident on Level Nine. There were no witnesses except two other Unspeakables. Tessa was one of them."

Something unpleasant twisted in Caroline's gut. "Was the other one named…Silas?"

Klaus stiffened immediately. "How do you know that?"

"He's _here,_ Klaus. Visiting Amara. And I'm pretty sure he's in love with her."

"He's dangerous, Caroline," Klaus said, gripping her tighter and looking towards the door as if Silas was about to fling it open any second. "What did he say to you?"

"Nothing much, just said that Amara mutters stuff that doesn't make sense."

"So I take it she's in no fit state to tell us anything of worth?"

"Just some stuff about red strings—"

Klaus visibly started. "Red strings like…the ones in the Department of Love?" he asked disbelievingly. "She didn't even work there."

"Neither did I," Caroline reminded him dryly. "Why do you think Silas is dangerous?"

"There 's something off about him," Klaus answered, lips pressed into a firm line. "I don't know what it is, but I don't trust him."

"So…what do we do now?" Caroline asked quietly.

Klaus said nothing for a long moment. "We move on, we forget these people, we focus on ourselves." He gathered her closer, his voice begging her to listen to him. "This has nothing do with us, Caroline."

He was right, honestly. And so Caroline nodded, let him put out the light on his wand and lead them back into the brightly lit hallway. She tried as hard as she could to tell herself that there was no point in pursuing any of this.

It would've been easy too, if it weren't for the fact that just before the doors to the staircase closed behind them, she noticed two things:

First, a tall figure was standing in the corner of the hallway, almost completely out of notice. Silas watched them leave, his stare intense and unwavering.

Second, just before the doors closed, Caroline saw the flash of a bright red string between her and Klaus, connecting them.

Screw all of this. She wanted answers and she was damn well getting them.

* * *

Honestly, if there was one thing Caroline wished the Wizarding World had, it was the internet. If the Wizarding World had the Internet, then everything anybody knew about the Department of Mysteries could be in a Wikipedia article, and Caroline wouldn't be sitting in Three Broomsticks, hiding from Rebekah Mikaelson and her posse and hoping no Hogwarts students saw her sitting there.

She didn't know what she was doing, but she was officially in too deep to back out now. There was only one place Caroline could think could possibly hold answers for her: The Restricted Section of the Hogwarts Library. But since she was no longer a student, she had to enlist a current seventh-year to do the dirty work.

Thank god April Young still hero-worshiped her.

"Hi Caroline!" Speak of the devil, April Young slid into the booth opposite Caroline, unwrapping the thick yellow and black scarf around her neck. "Oh my god, it is so cool to see you back in Hogsmeade! Do you get a lot of time to visit? Is the Ministry busy? I mean I want to work in the Ministry too, but I hope I get to come back here because I love this place and I'm going to miss it so much when—"

"April!" Caroline interjected quickly, swiveling her head frantically to make sure no one was paying attention to them. "It's, uh, great. Work is great, here's great. Do you have the book I asked you for?"

April nodded eagerly, reaching into her bag and pulling out a thick black book with the title _The Long History of the Ministry of Magic: Second Edition._ The dusty cover looked like it hadn't seen sunlight in at least a century. "I have it here. Professor Binns didn't even ask why I wanted to take it out, can you believe that?"

Caroline could believe that actually, nobody would ever suspect sweet, sweet April of doing anything remotely dangerous. She almost felt bad for taking advantage of April's willingness to please people, but this was necessary.

"So, is Kol here too? Is he visiting Rebekah?" April was a second away from calling out to the blonde Mikaelson but Caroline stopped her in the nick of time.

"He's not here! And Rebekah can't know I'm here because I'm…planning a surprise! For Kol. And it has to do with that book."

There was literally no part of that excuse that made sense, and even April's naivete looked like it was being stretched to its limits. But Caroline didn't care, the second Rebekah saw her there, Kol and Klaus would know, and Caroline was so close to getting the answers she needed.

April began babbling about what S.P.E.W was doing for their next fundraiser, and Caroline forced herself to sit still and nod politely, pretending to be interested in whatever April was saying. Normally she'd want to know if things were falling to pieces without Caroline to head the committee meetings, but the book in the corner of her eye was calling to her and Caroline could barely contain herself.

 _Finally,_ April rose to head out so that she could get back to the school on time. Caroline promised to have the book back to her by next week, and as soon as every Hogwarts student had cleared out, Caroline grabbed her things and ran outside, nearly splinching herself when she apparated home.

Kol — bless his philandering heart — was spending the night with his latest fling, so she had the place to herself. With near reverence, she pulled out the heavy tome and put it on the coffee table, watching it warily. Before, she'd been so eager to just get the answers she wanted, but now, she wasn't sure what she would find and if she wanted to find it.

It didn't even make sense that a book about the Ministry of Magic was in the Restricted Section, but Caroline suspected she was about to figure out why. Gingerly, she opened the book.

Nothing jumped out, screamed, hexed her, or tried to steal her soul. Always a plus.

Emboldened, Caroline flipped through the pages until she reached chapter nine. Unlike the rest of the book, several passages were crossed out angrily, or when Caroline tried to focus on a sentence, the letters jumped around the page, making it nearly impossible to understand what was right in front of her. The letters were minuscule and it gave her a headache the more she concentrated.

It took a full ten minutes before Caroline could make out the words "Department" and "Love" and she determined she had the right page. Her heart nearly leapt out of her throat when she managed to read 'strings'. One hour later, she finally managed one sentence.

 _Current research holds that the strings tie witches and wizards to their individual, unique soulmate._

Caroline swore her heart stopped.

 _Soulmate_

Was…was that a thing? Was that a Wizarding World thing? Soulmates were the stuff of Muggle fairytales, she'd never once heard anybody at Hogwarts talk about it like it was a normal, everyday occurence.

 _The strings tie witches and wizards to their individual, unique, soulmate._

Did that make her and Klaus…soulmates?

Caroline sat paralyzed on the couch, thinking back on everything that had ever happened between them, all the way back to the day in the Department behind the door that should've been locked, the strings that stretched high above them, all the love in the world…

Did the string that had attached to her and Klaus force them into being soulmates? Or did it find them because there was a magic in love that nobody could explain?

" _Find your one"_

A pleasant sort of ache formed in her heart the more she thought about it, the entirety of their relationship. The moments when it was just the two of them, when they lounged in bed, sweat slicked bodies entwined in expensive sheets, nothing in the world to worry about except each other and how much they loved each other.

Tentatively, Caroline held onto her memories of Klaus, letting them take over as she raised her left hand and stared at her pinky finger.

Every moment, every word, every feeling, she played it again and again, the ache in her chest growing until it threatened to overwhelm her and Caroline would gladly let it.

And finally there it was, the bright red string around her finger, stark and unbreakable. It trailed on the ground, through the apartment, and under the front door. Caroline didn't need to ask where it ended up.

Soulmates. She and Klaus were _soulmates_. 'Ones', Tessa and Amara had called it. She was no closer to figuring out what happened to Amara, but nothing mattered at the moment because Klaus was her soulmate and the only thing she wanted to do was tell him.

It was just too bad someone else would stop her before she got the chance.

* * *

Wherever Caroline was waking up, there was a pleasant warmth on her face. It prolonged her panic, making her feel safe despite the edges of her mind screaming danger. Her head ached, and her eyes opened slowly only to be assaulted by light —but it was still so warm, so safe, that she couldn't really be that bothered by it.

Until she really took in her circumstances, then she was _very_ bothered.

She was sitting in a chair, her limbs unnervingly still and with mounting panic, she realized that she couldn't move them, couldn't crane her neck around frantically. Marbled tile stretched out underneath, covering the large room with a fountain to her right, steam spiraling from mother-of-pearl liquid that gushed liberally. Caroline didn't have to look up to know what she would find — no source to the warm light that bathed the room but instead a mass of red strings crisscrossing a cavernous ceiling.

This was the room dedicated to Love in the Department of Mysteries, but she had no clue how she'd gotten here.

Her mind raced as she tried to recall her last memories. She'd been reading the book about the Ministry, she'd read about soulmates, she'd come to tell Klaus…

Klaus was supposed to be working late, she knew that, she'd come straight to the Ministry, gone down to Level Nine, nearly sprinted to the door—and that was when everything went black. She'd never even made it into the Hall of Prophecies, she had no idea where Klaus was or what was happening and her breaths started coming out rapidly, the spell constricting her only ratcheting up her horror. Her wand was nowhere in sight.

Soft footsteps sounded somewhere from her left until a person crossed into her line of vision.

"You can relax," Tessa said, smiling coldly. "There's no getting out."

Caroline wanted to speak but the body-bind curse kept her still and terrified. Tessa bent down until she was at eye level, reaching out to play with one of Caroline's curls. "I didn't think I'd get a chance like this."

Caroline could only stare back, trying to mask her terror with bravado.

Tessa regarded her in silence for moment before glancing down, where her hands rested on the arms of the chair. She looked at Caroline's pinky finger, pursing her lips together tightly before snapping her gaze back up to the blonde's. "I never paid attention to Mikaelson but I knew he was sleeping with some slut from Level One. Then I saw you…and I knew. I've worked here for so long, I knew immediately."

Tessa stepped back, rocking back and forth on her heels with a slightly manic glint in her eyes. Caroline tried to follow her movements the best she could.

"It's rare, you know. But now that you're here, I have what I've been waiting for." Tessa wandered over to the center of the room, staring up at the mass of red strings thoughtfully. "Witches and wizards have spent years in here trying to understand soulmates," she said, more to herself than anything. "And I thought if I could understand the magic, then I could control it."

Caroline didn't know why Tessa was taking her time to gloat, but the way the other woman seemed to savour the moment probably meant that this was the first time she'd been able to share whatever the hell went on in this room. The other witch turned, looking at Caroline for a moment, before waving her wand and suddenly Caroline found she could move her head again.

"What the hell is going on?!" she demanded but Tessa just relished the chance to have someone to talk to.

"I told you — you're going to help me understand soulmate magic."

"Why do this, why not just find someone to help?"

Tessa smirked, "Because there's a good chance this isn't going to end well for you…or Mikaelson."

Caroline's blood turned to ice, any thought of Klaus being in danger sent her into pure, unadulterated terror. Whatever fear she felt was herself was dwarfed in comparison, and her singular focus was somehow keeping Klaus safe. Whatever Tessa wanted, it would have to be with her only.

"What happened to Amara?" Caroline asked desperately, "What did you do to her?"

Tessa's demeanor changed then, her face twisting into something ugly and hateful. "That damn _bitch._ Everything would've been fine if it wasn't for her!"

"What happened?" Caroline asked, trying to keep her voice even and Tessa's attention focused on her.

"She did the same thing you did," Tessa snarled. "Wandered in where she had no business being. And she ruined _everything."_

Caroline gulped, "What did she do?"

Tessa stalked forward, leaning down until she was crouched in front of Caroline again. Screwing up her face in concentration, she muttered a spell under her breath and flicked her wand over Caroline's hand. The string around her finger glowed a bright red and Tessa eyed it hungrily.

"It doesn't matter what Amara did," Tessa said quietly, reaching down and picking up the string. "It matters what I'm going to do to _you."_

And then she pulled.

* * *

Klaus paced around his flat's living room, mulling over the events of the last few days. To think, he had Caroline naked and wanting in his bed not a week earlier — and now, he didn't know where they stood.

That was probably over-dramatic, it wasn't as if she'd demanded he stay away and never speak to her again. But she'd felt at least a little betrayed by his reluctance to tell the truth, even if he didn't know the full story himself.

Honestly, he hadn't cared about Amara Petrova past the fact that her loss was his gain. He'd wanted to be in the Hall of Prophecies and that was that. Amara's sudden turn for the worse had been too convenient for him to question, and Elijah had been too happy that his brother was willing to take a spot in the Ministry without fuss. Esther's approval of the whole affair was the final nail in the coffin — for a fleeting moment, Klaus had wondered if the Mikaelson matriarch hadn't somehow orchestrated the whole thing herself.

But Esther's hands were clean(of this) and no one knew what had happened to Amara, as much as Klaus now wished he had asked more questions at the time. Caroline had avoided him for the past few days, and whatever she was doing, Klaus didn't doubt for a second that it involved getting the answers she was looking for, with or without his help. And if trying to move past it meant that they were on different sides of this, then Klaus couldn't take it anymore.

Caroline wanted answers and he was going to help her get them, that was that.

He was set on his plan, halfway to the door when a sudden sharp, flaring pain sent him to his knees, his vision nearly whiting out. He didn't know if someone had cursed him, there was absolutely no one in his flat, and this felt like nothing he'd ever been prepared for in his old Defense Against the Dark Arts classes. The pain is sharp and intrusive and _wrong,_ it feels perverse—

' _Don'thurtKlausdon'thurtKlausdon'thurtKlaus'_

Klaus gasped, bracing himself from collapsing completely. The mantra beat in his head, steady as a drum, and it came with a voice he knew well.

"Caroline…" he whispered desperately, his fear turning to steely resolve. As suddenly as it came, the pain receded, leaving him clear headed on the floor. Caroline was in danger and he was damn well going to find her.

* * *

If Caroline's limbs could move, she was sure she'd be convulsing. The sharp, strange, alien pain of Tessa pulling on her red string had been fierce and unbearable, but no matter how much it _hurt,_ Caroline hadn't been scared for herself.

She'd been terrified for Klaus.

She knew, on the same instinct that had once told her she was different from all the other children in her neighbourhood growing up, that whatever Tessa had done to her by pulling on her string would affect Klaus too. And whatever the hell was going on here, she didn't want him in danger.

Caroline's limbs burned under the weight of immobility, Tessa smirking over her. "What are you going to do to me?" she whispered hoarsely.

In response, Tessa reached inside her robes, pulling out what looked like antique shears, gleaming silver in the light. She inspected them carefully, running her thumb along one of the blades, glancing between them and Caroline. "I've had these for a long time," she said finally. "No one knows where they've come from. No one knows what they could do. These _should_ be locked in a vault, but then, so few people understand what we study here. No one understands the implications."

The witch made no sense at all and Caroline wanted to snap at her to stop speaking in riddles, but the more Tessa gloated, the more time Caroline had to come up with a way out.

Unfortunately, it looked like time had run out.

Tessa bent down, shears in one hand, picking up Caroline's red string with the other. "I just need to understand," she muttered, more to herself than anyone. "If I could understand…"

She held the string delicately between two fingers. Caroline waited for the pain to come, but Tessa didn't bother, instead holding the string aloft and positioning the shears to cut.

Caroline wanted to scream, but the dread stopped her cold.

"What the hell are you doing?"

Tessa stilled. The question had come from behind her.

" _Help!"_ Caroline screamed, and immediately saw stars as Tessa viciously backhanded her, but Caroline could taste freedom and that didn't stop her from snapping her head back as soon as she could, trying to see who her would-be saviour was. She hoped, desperately, fervently, that somehow, some way, it was the person on the other end of her string.

It wasn't — the man who strolled into the room had a square jaw and disturbingly empty eyes — but even Silas was welcome right now.

"Please help me," Caroline begged, "she's crazy, she's trying to…"

She trailed off. Not because she couldn't manage it, but because she realized that Silas didn't looked shocked or appalled or even a little surprised to walk into a room with a door that should always be locked to find an Unspeakable keeping a woman cursed to a chair.

Whatever hope Caroline had died a quick death.

"You started without me," Silas said, almost sounding bored. He stalked forward until he stood right next to Tessa, looming over Caroline. His stance remained nonchalant, but as soon as he caught sight of the red string around Caroline's finger, there was no hiding the hungry gleam in his eye and his lips curved into a dark smile that didn't reach his eyes.

"I had a chance, I took it," Tessa snapped back.

Silas shrugged, his eyes still not leaving the string. "I'm not complaining."

Caroline's curiosity won over her horror, "Why are you helping her?!"

Silas's gaze slid over to Caroline's and the blonde barely suppressed a shudder at the coldness of it.

"I'm not helping her — she's helping _me."_ Silas said. "Or rather, she's fixing the mess she made." He looked over at Tessa with a sneer on his face and Caroline watched the other Unspeakable stand tall under his stare, but her hands shook, ever so slightly.

"I'm cutting her string," Tessa said through gritted teeth.

"Wait!" Caroline demanded, looking between Silas and Tessa. "Tell me what happened to Amara, what did you do to her?!"

Silas' calm facade dropped then, anger and pain twisting his features. "Go ahead!" he said mockingly, turning to Tessa. "Tell her what you did!"

Tessa's stance faltered for the first time and she couldn't meet Silas's stare anymore, leaving the man to scoff disdainfully.

"I work in one of the other Rooms," Silas explained, quiet and deadly. "Amara was in the hall of prophecies. One day, the door to this room was open…and we walked in."

"She had no business being here!" Tessa spat, but Silas barely paid attention to her, lost in the past.

"The string came down from the rest," he whispered, staring up at the huge nest, "tied itself around our fingers. We didn't know what it meant. We didn't care."

Caroline was reminded of the way Silas had sat by a hospital bed, nothing but naked adoration in his eyes. She didn't doubt for a second that Silas and Amara could have been soulmates.

A new fear washed over her. "Was it the string that did…whatever happened to her?"

Silas laughed, it held no humour. "No, it wasn't the string." He cut his furious stare over to Tessa again, who had turned her back on the both of them. "Tessa _fancied_ me."

Tessa spun on her feel, "Do _not_ pretend that you didn't lead me on!" she snarled. "But the minute that stupid string tied itself around you and that bitch—"

"Don't you dare!" Silas growled, pulling out his wand. He stopped himself at the last second, turning back to Caroline and realizing there was a bigger picture. "Amara and I didn't know what the string meant, but _she_ did. And she decided she didn't want it linking us anymore."

The story was coming together in Caroline's mind, hazy and terrifying. "What did you do?" she asked Tessa, trying to sound as neutral as possible.

"I fed him a love potion. Gave him the shears and told him to cut his own string, then destroy it."

Stifling silence descended over them. The only sound was the light bubbling of the fountain of Amortentia near them, and Caroline didn't have to guess twice where the supply Tessa had slipped Silas had come from. This was nothing like what sixth-year girls would whip together in their Hogwarts dormitories, this would have been so much worse. But cutting the string…

"Why was only Amara affected?" she asked quietly.

Silas shrugged, and the mask of bored disdain was back. "Because I was the one who made the cut? As soon as I did…the pain was enough to bring me back."

Caroline stared at the shears in Amara's hand and the truth dawned on her, slowly, horribly. "You made Silas destroy his string…so you want mine and Klaus's."

Silas's smile was feral. "And when we take yours, I'll be able to tie myself and Amara back together and we'll be happy."

There was no reasoning with someone that deep into his guilt and Caroline didn't even bother staring at him. Instead she stared at Tessa, whose face was perfectly blank, not guilty, not angry, not jealous….just blank.

"You're not going to let him do that, are you?" Caroline asked insistently. "You want to tie the string to yourself!"

Tessa slapped her across the face again, and this time, Caroline tasted blood. "I'm right, aren't I?!" She turned to Silas, "Don't you get it? She's not going to help you!"

Silas watched Tessa carefully, but he was clearly too far gone to care. They both were. "Get it over with."

Tessa picked up the string again, positioned her shears and Caroline sucked in a breath, hoping desperately that Klaus would survive this, that he wouldn't end up in St. Mungos next to Amara, that he would survive this and find happiness.

God, she wanted him to be happy.

The shears closed.

The pain was blinding.

" _CAROLINE!"_

* * *

Klaus stood at the entrance to the chamber with his wand at the ready, staring at Caroline's prone form in the chair. Silas was on his feet, but Klaus was the quicker dueler, disarming him easily.

"Get away from her," he growled, marching forward. Tessa let something silver clatter to the floor and pulled out her own wand but Klaus saw her coming.

" _Stupefy!"_ Tessa went down, and Caroline suddenly slumped forward, the spell keeping her stuck to the chair finally broken. Klaus rushed for her, skidding to the ground and pulling her into him, checking her over for injuries, a heavy wave of relief crashing over him when he found none.

"Caroline— love, are you alright?" he asked. She was dazed, eyes unfocused, and stared up at him like she couldn't believe she was seeing him. But as soon as clarity returned to her eyes, she gasped, and lifted her left hand to her face.

Klaus didn't know how he hadn't noticed it as soon as he stepped inside the room, but there it was, a bright red string around her finger, now pooled on the floor between them, the other end connecting to Klaus's own hand.

"We're soulmates," Caroline said, first in whisper and then again, louder and with a growing smile. "Klaus, the strings, they connect _soulmates."_

Her smile was dazzling even though she made no sense but that didn't matter to him, because in the next second she had thrown her arms around his neck and pulled him into a kiss, equal parts love and relief. He returned the gesture in kind, the solid weight of her in his arms a reassurance that he had found her in time, that she was _fine,_ and if he had anything to say about it, she would always be safe.

"How did you find me?" she whispered against his lips.

Klaus pulled back so that he could look her in the eyes, one hand holding her cheek, stroking it. "I felt some sort of pain, I knew it was you," he explained hurriedly, "I followed — I don't know what I followed. Some instinct led me here."

"You followed the string," Caroline said, eyes wide as she looked down at it again. "It connects us because we're _soulmates._ "

"Sweetheart, I've never heard—"

"It's true," Caroline said firmly.

"She's right, you know."

Klaus snapped to attention, cursing his stupidity. He'd been so focused on getting to Caroline that he neglected to realized Silas had retrieved his wand and was ready to put up a fight. Klaus rose to his feet, dragging Caroline up with him and placing himself firmly in front of her. "What do you want?" he growled.

"I want _my_ soulmate back. And I'm willing to do whatever it takes to get it."

Klaus raised his wand, but before either of them could do anything, a sharp voice rang out, _"Locomotor Mortis!"_

Tessa picked herself up from the ground, wand pointed out at Klaus and Caroline. The leg-locker curse took hold immediately, dropping them back to the ground, and Klaus felt his wand being wrenched from his hand and thrown to the other side of the chamber. A flick of Silas's wand and Klaus was pulled away from Caroline, a sudden chasm of space between them.

They were wandless, defenseless. Klaus didn't dare take his eyes off Caroline.

"I told you I'm willing to do whatever it takes," Silas snarled. "Cut the string!" he ordered Amara.

But Amara made no move to pick up the shears instead staring down at Caroline with an unreadable expression. "It has to be one of them," she said to herself before looking up at Silas. "It has to be one of them! _You_ were the one who cut your string, it doesn't work if anyone else does it!"

Silas nodded, absorbing the information quickly. "Go on then," he barked at Caroline, nodding towards the shears near her hand. "Cut it!"

Caroline shook her head immediately, not even wincing when Amara aimed her wand at her.

" _Do it!"_

Caroline remained steadfast. "You'll have to kill me," she spat.

Silas smirked coldly. "Why would we do anything to _you_?"

Klaus realized his meaning seconds before Silas raised his wand.

" _Crucio."_

Klaus tried to keep his composure, but every nerve was on fire, every inch of his body felt like a knife was sliding through his skin, piercing his insides and twisting them until there was nothing left of him. As soon as it ended he slumped forward, legs still locked and arms braced against the floor as he panted heavily, sweat beading on his forehead. His heartbeat roared in his ears but through the noise he heard Caroline screaming for them to stop, begging them to turn on her.

 _No._ Whatever they did to him, he couldn't let them touch her.

"Don't hurt him," she begged, "whatever happens, you swear that nothing happens to him!"

"He'll be fine," Silas said curtly.

"Caroline…" Klaus croaked, the aftereffects of the Cruciatus Curse still exhausting him. "Don't, _please."_

"It's going to be fine," Caroline soothed, picking up the shears with trembling hands. "Just…don't look, okay?"She managed a watery smile, trying to suck up her fear, but Klaus could see right through her. He always could.

"Don't do this," he begged.

"Shh," Caroline said, blinking away her tears. "I love you."

She'd never said that before. He knew, somehow, but they'd never actually said the words.

"I love you too."

Caroline choked out a sob, and Klaus felt the press of Silas's wand against the back of his neck.

"Cut the fucking string."

Caroline kept her stare on Klaus, and with a shuddering breath, she raised her left hand and held the shears straight in front of her, closing the blades around the string.

For a moment, Klaus swore everything stopped.

Then everything went white.

Something warm and blinding swept rippled out throughout the chamber, knocking Silas and Tessa to the ground, and Klaus felt his legs come free. He wasted no time with spells, simply grabbing Silas and punching the bastard across the face. His wand was on the other side of the chamber and he ran for it, not willing to be taken down again, but when he had it firmly in his grasp, he saw that Silas was out cold and Tessa had followed suit.

And Caroline…

Caroline was staring at her left hand where the red string between them glowed brightly, whole and unbroken.

* * *

"Do I even want to know how this started?"

Elijah received no answer to his question, but Caroline doubted he actually expected one. She watch the Aurors float Tessa and Silas's unconscious bodies away, taking them somewhere they could be held for questioning. And there would be questions. And eventually Caroline herself would have to answer them, but for now, Klaus had done an admirable job of using his family connections to keep everything as low-key as possible.

Few wizards or witches were allowed down here anyway, so the pair were only faced with scrutiny from Elijah and Kol, the former who would be doing everything in his (considerable) power to cover up all that had happened, and the latter who just wanted to sneak a peek at the carnage, but was currently eyeing the red string between Klaus and Caroline.

"You'll have to sit through a formal inquiry," Elijah explained, running a hand over his face tiredly. "But if Silas used an Unforgivable Curse…"

"He did," Caroline finally spoke up, her voice hard.

Elijah nodded gravely, rare concern showing as he looked over his younger brother, noting the way him and Caroline leaned on each other. "Well, the Veritaserum will confirm that, and then he won't be a problem. Tessa will likely face similar consequences, once the full story comes out."

Klaus nodded and Elijah could see the exhaustion on both their faces, so he let them go for now. "We'll sort through the details tomorrow, get some rest." He clasped his hand on Klaus's shoulder and with a nod, turned on his heel. Kol lingered, and stared up at the nest of red strings criss-crossing the ceiling.

"Can I assume I have the flat to myself tonight?" he asked Caroline with a wink and she rolled her eyes half-heartedly. "Well, I'll be off to take advantage. Try not to get into too much trouble."

He copied Elijah and clasped Klaus on the arm in a rare display of brotherly affection, then darted forward and pressed a quick kiss to Caroline's cheek. The most he'd ever do to show that he was concerned about either of them. "Have fun in bed!"

Kol was gone before either of them could yell after him and then it was just Klaus and Caroline and the room filled with the mystery of Love. Even despite what had happened, it was warm and comforting in a way Caroline only really understood when it was just her and Klaus, with nothing else in the world to care about.

"What now?" Klaus asked, question after question running through his head.

There was so much to talk about, but this conversation she could have. "Now we go home."

* * *

It was raining again, to no one's surprise. Klaus locked the door of his apartment behind them and as an afterthought pulled out his wand and tapped it against the handle. "Extra measures," he said with a shrug, "I doubt we'll want to be interrupted by Muggle or magic."

Well, Caroline couldn't argue with him there.

They stood in silence for a long torturous moment, neither knowing what to say. Caroline knew what she wanted, she wanted to feel him fully and completely, with the knowledge that they were _it_ for each other, that there was a magic between them that was so deep and powerful that no one could take it away from them. But it was almost overwhelming— almost.

"The string." Klaus finally broke the silence, glancing down at his hand, but of course he couldn't see it anymore, it had disappeared the moment they'd both stepped out of the Department.

"Watch this," Caroline whispered, a small smile on her face. She closed her eyes and concentrated on Klaus, on how much she felt for him, enough that her chest ached but she wanted more, and when she opened her eyes, she saw the bright red colour of the string connecting the two of them, Klaus's mouth hanging open. It disappeared slowly after a few moments but there was no denying that it was there, that it would _always_ be there.

"And it means you're my… _One?_ " he asked,coming closer, fingers itching to pull her closer.

Caroline met him in the middle, raising up a hand to cup his cheek and run her thumb over the stubble on his chin. "Soulmates," she confirmed quietly. "We're soulmates."

Klaus couldn't wait any longer, he leaned down and closed the space between them, meeting her lips with his. His hands found their way to her waist, grasping her close as if someone was going to try and tear them apart again. Let them, Caroline thought.

She parted her lips and poured every ounce of love for him she could into it, the worry when she thought he'd be affected, the pain of seeing him under the Cruciatus Curse, the relief of having him safe and whole in front of her now. All of that and more, string or no string, he was everything for her and she ached for more of him.

"How did you find me?" she asked breathlessly when he finally pulled away.

"Followed instinct," he explained against her neck, pressing hot kisses against her skin, as if he were mapping her out for the first time. "Realized that I was following the string."

It made very little sense, but magic rarely did. Instead, Caroline let the word _soulmate_ play over and over in her mind on a loop while Klaus continued his ministrations, tugging the thin strap of her dress of her shoulder.

Caroline moaned at the feel of his stubble against her skin and backed away slowly, towards the direction of his bedroom. But the space was too much for him at the moment and he immediately grabbed her back, ignoring her small squeal as he picked her up and walked them down the hall to his bed himself.

Soft sheets met Caroline's back as Klaus dropped her down on his bed and she stared up at him with wide, lust-blown eyes, the two of them falling into another moment of silence before Caroline finally broke it.

"I love you."

Klaus was on her in the next second, pushing her dress up her thighs, kissing every inch of skin revealed to him. "Again," he growled against the lace of her panties, and Caroline lost her breath at the feel of warm mouth so close to where she needed him, separated by a maddeningly thin barrier.

"I love you," she moaned, "I _love_ you."

Her underwear was dragged down her legs a moment later by his teeth and then he was back, one arm solidly draped over her waist to hold her down as she arched against his mouth, tongue expertly parting her folds and working on her clit until she saw stars.. He drove her to the edge expertly, tongue drawing figures against her pussy, spelling out the indecent things he wanted to do to her, drawing out her release the way he'd perfected.

Caroline's hand flew to his hair, threading her fingers through his curls and she felt the tension in her grow and grow until Klaus had her tumbling over the edge, sobbing his name like a prayer.

"You're so bloody beautiful," Klaus whispered as he divested himself of his clothes and climbed over her pliant body, kissing her hard and Caroline tasted herself on his lips. "And you're _mine,"_ he whispered, picking up her hand where they knew the string was, invisible now, though Caroline swore she saw red in the corner of her eye.

"My soulmate," Klaus whispered against her skin, tearing her dress over her head so that there was nothing between them and he took full advantage, long artist's fingers reaching and caressing every possible inch of her. "There's on one else for us sweetheart, you're mine," Klaus said, never breaking eye contact before he bent his head down to lave his tongue around her nipple, his fingers tweaking the other one into a peak, taking great pleasure in watching her come undone.

"Please, Klaus," Caroline whined, as talented as his fingers and tongue were, she needed so much more from him.

"I love you like this you know," he commented idly, as if he wasn't just as gone for her as she was for him. "Naked and needy, wet and wanting. And now I know I get to have like this _forever,"_ he growled, blatant possessiveness running through him as she ran his hands over him, trying to pull him down for another kiss. He let her, but pulled away and grabbed her hands, pinning them above her head as he positioned himself between her thighs.

" _Please,_ Klaus, I need you," Caroline panted, not even caring how desperate for him she sounded.

"Need what?" Klaus asked with a filthy smirk, fully intending on drawing out every inch of desire she had in her. One hand kept her hands pinned, the other went to stroke his cock as she watched him with naked want. "Use your words, love."

"I need your cock," Caroline said, meeting his heady stare. "I need you inside me."

"Good girl," Klaus replied, bending down to peck her lips. He swiped a hand through her folds, finding her soaking wet and nearly came over her. "Tell me more?"

"I need you to fuck me," Caroline whispered against him, " _Ineedyouineedyouinneedyou—"_

His own desperation couldn't hold out any longer and he slid into her easily with one thrust, settling for a moment as he let her adjust, and then moved against her, rocking his body against hers with what little finesse he could manage considering how achingly perfect she felt around him, wet and warm and tight as if she alone were made just for him. And maybe she was, all things considered.

Klaus finally abandoned the hold on her wrists, letting her wrap her arms around him as he pulled her up with him so that he was on his knees, leaning back on his haunches and she was rocking in his lap, gasping at the angle this position afforded them. His lips ravaged her skin, leaving marks that he would happily admire the next morning, reminders of the magic that bound them.

Caroline felt his control slip, and he fucked her harder, gripping her tighter. Her fingers tugged on his curls, hard, and she moaned against his lips at the slap he delivered against her outer thigh in response. Her pussy gripped him tighter and he buried his face against her neck as he came, stilling against her. He played with her clit until she came apart for a second time a moment later and together they collapsed backwards onto the bed, skin slicked with sweat, limbs tangled and Klaus still buried inside her.

"Mine," he whispered again, gentler this time.

"Yours," Caroline agreed wholeheartedly. She groaned at the pleasant ache she felt as he pulled out of her, moving away only so far as to pull the heavy duvet over the two of them, and Caroline felt him tangle his legs in between hers as he pulled her closer, nose skimming the back of her shoulder.

"Rest up," he said fondly, dropping a kiss to the back of the neck. "I intend to keep you busy all night."

" _You_ should rest," Caroline protested weakly. "It's been a long day."

"On one condition — we take tomorrow off."

"I'm pretty sure Elijah expects us to answer questions about what happened today."

"He can fuck off until I've had my fill of you." Klaus said with finality, and Caroline had no doubt he'd duel his brother if it meant keeping her in bed.

"Fine," Caroline said without much of a fight. "But we might be here a while."

"Forever, love, if I have anything to say about it."

* * *

"Ready to head out, sweetheart?"

Caroline looked up from her desk at her boyfriend poking his head into her office, grinning widely. "How did you get in here?" she asked, already waving her wand to clear the paperwork off her desk.

"Would you believe that the door doesn't lock for me anymore?" Klaus asked, coming inside and meeting her halfway, greeting her with a kiss. "The room just lets me in."

"Wonder why?" Caroline asked aloud, but felt like she already knew the answer.

The Department of Mysteries had no shortage of enigmas for the people who worked there, and Caroline privately thought that every room had enough magic that no witch or wizard would ever be able to figure out, no matter how many years of research they put into it. Not that she was about to stop trying. Tessa was looking at a long stay in Azkaban along with Silas, and the Room which housed the mysteries of Love needed a new Head Researcher.

After the rumours had spread, there hadn't been a lot of people jumping to take the position. Except one.

Elijah was sorry to lose her and had implied not so subtly that he'd be happy to give her a position in his hypothetical cabinet one day. But for the first time, Caroline was ready to deviate from her life plan if it meant taking the position here, in the Department of Mysteries, trying to understand the power behind the red string that was now always visible within the chamber outside her office. There was so much raw power in love, she wanted to understand all of it.

Klaus had wholeheartedly supported her career change.

"How goes the search for a remedy?" Klaus asked as Caroline pulled her coat over her robes.

"No luck," she replied a little sadly. "Amara may be permanently damaged. I'm visiting her this weekend." Even if it was just to leave flowers and make her smile, Caroline couldn't help but feel sorry for the witch who had been a victim of love and jealousy, and now had no one coming to visit her. "Silas was a lunatic…but he loved her. I can't imagine what it must have been like to realize he'd cut his string."

"Love is powerful," Klaus said with a shrug, "and dangerous."

"Very," Caroline agreed. "But at least I still like you."

Klaus smirked at her cheek, tugging her close as soon as she'd gathered the last of her things. "Only until we both get fired for workplace indecency."

Caroline hid her smile against him as he tucked her under his arm and pulled her out of the office that was hidden in the back and across the marble floor of the chamber, warm light making her feel safe and loved as it always did. Before they left, Caroline glanced up, at the nest of red strings, each one for soulmates who were out there, already in love or just waiting to find each other.

All that love, with the capacity to become dangerous on the turn of a knife. But then she glanced up at Klaus, who stared back with nothing but adoration.

Love was dangerous. Love was powerful. But she had it, and she wouldn't trade it for all the magic in the world.

* * *

 **For anyone whose unfamiliar with the myth, the 'Red Strings' come from Japanese folklore which held that the gods tied a red string between the little fingers of two destined lovers. I thought it made sense to weave that into the Department of Mysteries.**

 **Hope you enjoyed!**


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